Method for forming resin cured film pattern, photosensitive resin composition, photosensitive element, method for producing touch panel, and resin cured film

ABSTRACT

The method for forming a resin cured film pattern according to the invention comprises a first step in which there is formed on a base material a photosensitive layer composed of a photosensitive resin composition comprising a binder polymer with a carboxyl group having an acid value of 75 mgKOH/g or greater, a photopolymerizable compound and a photopolymerization initiator, and having a thickness of 10 μm or smaller, a second step in which prescribed sections of the photosensitive layer are cured by irradiation with active light rays, and a third step in which the sections of the photosensitive layer other than the prescribed sections are removed to form a cured film pattern of the prescribed sections of the photosensitive layer, wherein the photosensitive resin composition comprises an oxime ester compound and/or a phosphine oxide compound as the photopolymerization initiator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/062,996, filed Mar. 7, 2016, which is a continuation of U.S.application Ser. No. 14/362,726 filed on Jun. 4, 2014, which is a U.S.national phase application filed under U.S.C. §371 of InternationalApplication No. PCT/JP2012/081383 filed Dec. 4, 2012, designating theUnited States, which claims priority from International Application No.PCT/JP2011/078104 filed Dec. 5, 2011. The contents of each of theabove-referenced U.S. and International applications are herebyincorporated herein by reference in their entirety for all purposes.

TECHNICAL FIELD

The present invention relates to a method for forming a resin cured filmpattern, to a photosensitive resin composition, to a photosensitiveelement, to a method for manufacturing a touch panel and to a resincured film.

BACKGROUND ART

Liquid crystal display units and touch panels (touch sensors) are usedin display devices including large electronic devices such as personalcomputers and televisions and miniature electronic devices such as carnavigation systems, cellular phones and electronic dictionaries or OA•FAdevices. Such liquid crystal display units and touch panels are providedwith electrodes composed of transparent conductive electrode materials.As transparent conductive electrode materials there are known ITO(Indium-Tin-Oxide), indium oxide and tin oxide, which materials exhibithigh visible light transmittance and are therefore the major materialsused as electrode materials for liquid crystal display unit boards.

Various types of systems are already being implemented for touch panels,but in recent years the use of electrostatic capacitive touch panels hasbeen progressing. In an electrostatic capacitive touch panel, contact ofthe fingertip (a conductor) with the touch input screen causeselectrostatic capacitive coupling between the fingertip and theconductive film, forming a condenser. Thus, an electrostatic capacitivetouch panel detects changes in electrical charge at sites of contactwith the fingertip, thereby determining the coordinates.

In particular, projection-type electrostatic capacitive touch panelshave satisfactory operativity allowing complex instructions to becarried out since they allow multipoint fingertip detections, and theexcellent operativity has led to their utilization as input devices onthe display surfaces of devices with small displays such as cellularphones, portable music players and the like.

For representation of two-dimensional coordinates with an X-axis and aY-axis, a projection-type electrostatic capacitive touch panel generallyhas a plurality of X-electrodes and a plurality of Y-electrodesperpendicular to the X-electrode forming a two-layer structure, with ITO(Indium-Tin-Oxide) employed as the electrodes.

Incidentally, since the frame region of a touch panel is a region wheredetection of the touch location is not possible, reducing the area ofthe frame region has been an important goal in order to increase productvalue. The frame region requires metal wiring in order to transmit thedetection signal of a touch location, but the width of the metal wiringmust be narrowed to reduce the frame area. Because of the insufficientlyhigh conductivity of ITO, metal wirings are generally formed of copper.

However, in the touch panels mentioned above, corrosive components suchas moisture and salts can infiltrate from the sensing region into theinterior upon contact with the fingertip. When corrosive componentsinfiltrate into the interior of a touch panel, the metal wiring maycorrode, electrical resistance between the electrodes and drivingcircuits may increase, and wire breakage can occur.

In order to prevent corrosion of metal wirings, there have beendisclosed electrostatic capacitive projection-type touch panels withinsulating layers formed on metals (Patent document 1, for example). Insuch touch panels, a silicon dioxide layer is formed on metal by aplasma chemical vapor deposition method (plasma CVD), thereby preventingcorrosion of the metal. However, because such methods employ plasma CVD,they require high-temperature treatment, and therefore the basematerials are limited and production cost is increased.

Incidentally, known methods for providing resist films on necessarylocations include methods in which a photosensitive layer comprising aphotosensitive resin composition is provided on a prescribed basematerial and the photosensitive layer is exposed and developed (Patentdocuments 2 to 4, for example). Also, Patent documents 5 and 6 discloseformation of protective coats for touch panels by such methods.

CITATION LIST Patent Literature

[Patent document 1] Japanese Unexamined Patent Application PublicationNo. 2011-28594[Patent document 2] Japanese Unexamined Patent Application PublicationHEI No. 7-253666[Patent document 3] Japanese Unexamined Patent Application PublicationNo. 2005-99647[Patent document 4] Japanese Unexamined Patent Application PublicationHEI No. 11-133617[Patent document 5] Japanese Unexamined Patent Application PublicationNo. 2010-27033[Patent document 6] Japanese Unexamined Patent Application PublicationNo. 2011-232584

SUMMARY OF INVENTION Technical Problem

Fabrication of a protective coat by a photosensitive resin compositioncan potentially reduce cost compared to plasma CVD. However, when aprotective coat is to be formed on an electrode for a touch panel, alarge thickness of the resin film can result in conspicuous leveldifferences between locations with the coat and locations without thecoat. The protective coat is therefore preferred to be as thin aspossible.

However, the present inventors have found that when a photosensitivelayer composed of a photosensitive resin composition is formed on a basematerial to a thickness of 10 μm or smaller and the photosensitive layeris patterned by exposure and development, the resolution tends to bereduced. Furthermore, although with the photosensitive resincompositions described in PTLs 5 and 6 it is possible to form aprotective coat with high transparency as a thin-film, there has beenroom for improvement in terms of pattern formation.

It is an object of the present invention to provide a method for forminga resin cured film pattern that allows formation of a resin cured filmpattern at sufficient resolution even as a thin-film, and aphotosensitive resin composition that can form a resin cured film havinga satisfactory pattern shape on a base material even as a thin-film, aswell as a photosensitive element, a method for manufacturing a touchpanel and a resin cured film.

Solution to Problem

As a result of diligent research directed toward solving the problemsdescribed above, the present inventors have found that by using aphotosensitive resin composition containing a specific binder polymer, aphotopolymerizable compound and a specific photopolymerizationinitiator, it is possible to form a satisfactory resin cured filmpattern having sufficient resolution even when the photosensitive layerhas been formed to a thickness of 10 μm or smaller, and the inventionhas been completed upon this finding.

The method for forming a resin cured film pattern according to theinvention comprises a first step in which on a base material there isformed a photosensitive layer composed of a photosensitive resincomposition comprising a binder polymer with a carboxyl group having anacid value of 75 mgKOH/g or greater, a photopolymerizable compound and aphotopolymerization initiator, and having a thickness of 10 μm orsmaller, a second step in which prescribed sections of thephotosensitive layer are cured by irradiation with active light rays,and a third step in which the sections of the photosensitive layer otherthan the prescribed sections are removed to form a cured film pattern ofthe prescribed sections of the photosensitive layer, wherein thephotosensitive resin composition comprises an oxime ester compoundand/or a phosphine oxide compound as the photopolymerization initiator.

According to the method for forming a resin cured film pattern of theinvention it is possible to form on a base material a resin cured filmpattern having sufficient resolution even with a thin-film where thethickness is 10 μm or smaller

The present inventors believe that the reason for this effect exhibitedby the method of the invention is as follows. Firstly, the presentinventors believe that one factor for the reduced sensitivity is that asmaller photosensitive layer thickness increases the effect of lightscattering through the base material, generating halation. The presentinventors presume that, according to the invention, the oxime site inthe oxime ester compound or the phosphine oxide site in the phosphineoxide compound has relatively high photodecomposition efficiency and asuitable threshold value such that it does not decompose with scantlevels of leaked light, and therefore the effect of leaked light isminimized and consequently sufficient resolution is obtained.

In the method for forming a resin cured film pattern of the invention,the photosensitive resin composition preferably further comprises anultraviolet absorber from the viewpoint of further increasing theresolution. Including an ultraviolet absorber will allow absorption ofleaked light in the photosensitive layer.

From the viewpoint of minimizing decomposition of the oxime estercompound or phosphine oxide compound by leaked light and furtherincreasing the resolution, the ultraviolet absorber is preferably onehaving a maximum absorption wavelength in the wavelength range of nolonger than 360 nm.

Also, from the viewpoint of further increasing the resolution,preferably the absorbance of the photosensitive layer at 365 nm is nogreater than 0.4 and the absorbance at 334 nm is 0.4 or greater. If thephotosensitive layer has such absorption properties, leaked light willbe absorbed more easily, and it will be possible to minimizedecomposition of the oxime ester compound or phosphine oxide compound byleaked light.

In the method for forming a resin cured film pattern according to theinvention, the photosensitive layer preferably has a minimum visiblelight transmittance of 85% or greater at 400 to 700 nm.

When a protective coat on an electrode for a touch panel is to beformed, a higher transparency is preferred for the resin cured film inconsideration of visibility and aesthetic appearance of the touch panel.With a conventional photosensitive resin composition, however,photoreaction is employed utilizing primarily light from the ultravioletregion to the visible light region, and therefore photoinitiatorcomponents are usually used that have absorption reaching the visiblelight region. Purposes requiring pigments or dyes are also common, inwhich cases it is difficult to ensure transparency. In contrast, in themethod for forming a resin cured film pattern according to theinvention, a specific photosensitive layer is formed and it isirradiated with active light rays, thereby allowing sufficientresolution to be obtained even when the minimum visible lighttransmittance of the photosensitive layer is 85% or greater.

Also, the photosensitive layer preferably has a b* value of −0.2 to 1.0based on the CIELAB color system.

This will make it possible to adequately prevent loss of visibility oraesthetic appearance even when forming a resin cured film pattern as aprotective coat on an electrode in the sensing region of a touch panel.

In the method for forming a resin cured film pattern of the invention,the base material may be provided with electrodes for a touch panel anda resin cured film pattern may be formed as a protective coat on theelectrodes.

Also, in the method for forming a resin cured film pattern according tothe invention, a photosensitive element is prepared comprising a supportfilm and a photosensitive layer composed of the photosensitive resincomposition provided on the support film, and the photosensitive layerof the photosensitive element can be transferred onto the base materialto provide the photosensitive layer. This will allow the photosensitiveelement to be used for simple formation of a protective coat with auniform film thickness.

The invention further provides a photosensitive resin composition forformation of a resin cured film pattern with a thickness of 10 μm orsmaller, which comprises a binder polymer with a carboxyl group havingan acid value of 75 mgKOH/g or greater, a photopolymerizable compoundand a photopolymerization initiator, the photopolymerization initiatorincluding an oxime ester compound and/or a phosphine oxide compound.

With a photosensitive resin composition of the invention it is possibleto form a protective coat having satisfactory pattern formability evenas a thin-film, on a prescribed electrode for a touch panel.

The photosensitive resin composition of the invention preferably furthercomprises an ultraviolet absorber from the viewpoint of furtherincreasing the resolution.

From the viewpoint of further increasing the resolution, the ultravioletabsorber is preferably one having a maximum absorption wavelength in thewavelength range of no longer than 360 nm.

Also, from the viewpoint of further increasing the resolution,preferably the absorbance at 365 nm is no greater than 0.4 and theabsorbance at 334 nm is 0.4 or greater.

From the viewpoint of sufficient visibility of the touch panel, thephotosensitive resin composition of the invention preferably has aminimum visible light transmittance of 85% or greater at 400 to 700 nm.

Also, from the viewpoint of further improving the visibility of thetouch panel, the photosensitive resin composition of the inventionpreferably has a value of −0.2 to 1.0 for b* based on the CIELAB colorsystem.

The invention further provides a photosensitive element comprising asupport film, and a photosensitive layer composed of a photosensitiveresin composition according to the invention, formed on the supportfilm.

With a photosensitive element of the invention it is possible to form aprotective coat having satisfactory pattern formability even as athin-film, on a prescribed electrode for a touch panel.

The thickness of the photosensitive layer may be 10 μm or smaller

The invention still further provides a method for manufacturing a touchpanel, comprising a step of forming, on a base material with anelectrode for a touch panel, a resin cured film pattern as a protectivecoat covering all or a portion of the electrode by the method forforming a resin cured film pattern according to the invention.

The invention still further provides a resin cured film composed of acured photosensitive resin composition of the invention.

Advantageous Effects of Invention

According to the invention it is possible to provide a method forforming a resin cured film pattern that allows formation of a resincured film pattern at sufficient resolution even with a thin-film, and aphotosensitive resin composition that can form a resin cured film havinga satisfactory pattern shape on an electrode for a touch panel even witha thin-film, as well as a photosensitive element, a method formanufacturing a touch panel and a resin cured film.

Also, the method for forming a resin cured film pattern of the inventioncan be suitably used to form a protective coat for an electronic partthat requires protection with a thin-film, such as a protective coat onan electrode for a touch panel, and particularly a protective coat for ametal electrode in an electrical capacitance-type touch panel.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view showing an embodiment of aphotosensitive element of the invention.

FIG. 2(A) is a schematic cross-sectional view for illustration of afirst step of an embodiment of a method for forming a resin cured filmpattern according to the invention; FIG. 2(B) is a schematiccross-sectional view for illustration of a second step of an embodimentof a method for forming a resin cured film pattern according to theinvention; and FIG. 2(C) is a schematic cross-sectional view forillustration of a third step of an embodiment of a method for forming aresin cured film pattern according to the invention.

FIG. 3 is a schematic top view showing an example of an electrostaticcapacitive touch panel.

FIG. 4 is a schematic top view showing another example of anelectrostatic capacitive touch panel.

FIG. 5(A) is a partial cross-sectional view of section C of FIG. 3 alongline V-V, and FIG. 5(B) is a partial cross-sectional view showinganother mode thereof.

DESCRIPTION OF EMBODIMENTS

Embodiments for carrying out the invention will now be explained infurther detail. However, the present invention is not limited to theembodiments described below. Throughout the present specification,“(meth)acrylic acid” refers to acrylic acid or methacrylic acid,“(meth)acrylate” refers to acrylate or its corresponding methacrylate,and “(meth)acryloyl group” refers to an acryloyl or methacryloyl group.Also, “(poly)oxyethylene chain” refers to an oxyethylene orpolyoxyethylene group, and “(poly)oxypropylene chain” refers to anoxypropylene or polyoxypropylene group.

Also as used herein, the term “step” includes not only an independentstep, but also cases where it cannot be clearly distinguished from othersteps, so long as the desired effect of the step can be achieved. Asused herein, a numerical range using “to” represents a range includingthe numerical values specified as the minimum and maximum values for therange.

Also, the contents of the components in compositions referred to herein,in cases where the composition contains more than one substancecorresponding to each component in the composition, are the totalamounts of those substances in the composition, unless otherwisespecified.

FIG. 1 is a schematic cross-sectional view showing an embodiment of aphotosensitive element of the invention. The photosensitive element 1shown in FIG. 1 comprises a support film 10, a photosensitive layer 20composed of a photosensitive resin composition according to theinvention formed on the support film 10, and a protective coat 30 formedon the side of the photosensitive layer 20 opposite the support film 10.

The photosensitive element of this embodiment can be suitably used toform a protective coat on an electrode for a touch panel.

As used herein, the term “electrode for a touch panel” includes not onlythe electrode in the sensing region of a touch panel, but also the metalwiring in the frame region. The protective coat may be provided for oneor both electrodes.

The support film 10 used may be a polymer film. Examples of polymerfilms include films made of polyethylene terephthalate, polycarbonate,polyethylene, polypropylene, polyethersulfone and the like.

The thickness of the support film 10 is preferably 5 to 100 μm, morepreferably 10 to 70 μm, even more preferably 15 to 40 μm and mostpreferably 20 to 35 μm, from the viewpoint of ensuring coverability andminimizing reduction in resolution during irradiation with active lightrays through the support film 10.

The photosensitive resin composition of the invention used to form thephotosensitive layer 20 comprises a binder polymer with a carboxyl grouphaving an acid value of 75 mgKOH/g or greater (hereunder also referredto as “component (A)”), a photopolymerizable compound (hereunder alsoreferred to as “component (B)”) and a photopolymerization initiator(hereunder also referred to as “component (C)”), and thephotopolymerization initiator includes an oxime ester compound and/or aphosphine oxide compound.

For this embodiment, component (A) is preferably a copolymer containinga structural unit derived from (a) (meth)acrylic acid and (b) an alkyl(meth)acrylate ester.

Examples for the alkyl (meth)acrylate include methyl (meth)acrylate,ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylateand hydroxylethyl (meth)acrylate.

The copolymer may also contain in the structural unit another monomerthat is copolymerizable with component (a) and/or component (b).

Examples of other monomers that are copolymerizable with component (a)and/or component (b) include tetrahydrofurfuryl (meth)acrylate,dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate,glycidyl (meth)acrylate, benzyl (meth)acrylate, 2,2,2-trifluoroethyl(meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate,(meth)acrylamide, (meta)acrylonitrile, diacetone (meth)acrylamide,styrene and vinyltoluene. For synthesis of a binder polymer as component(A), the monomer component used may be of a single type or a combinationof two or more types.

From the viewpoint of resolution, the weight-average molecular weight ofthe binder polymer as component (A) is preferably 10,000 to 200,000,more preferably 15,000 to 150,000, even more preferably 30,000 to150,000, yet more preferably 30,000 to 100,000 and most preferably40,000 to 100,000. The measuring conditions for the weight-averagemolecular weight are the same measuring conditions as in the examples ofthe present specification.

From the standpoint of excellent patternability, the acid value of thebinder polymer as component (A) is preferably 75 to 200 mgKOH/g, morepreferably 75 to 150 mgKOH/g and even more preferably 75 to 120 mgKOH/g.

The acid value of the binder polymer as component (A) can be measured inthe following manner

Specifically, a 1 g portion of binder polymer for measurement of theacid value is first precisely weighed out. A 30 g portion of acetone isadded to the weighed binder polymer to homogeneously dissolve it. Next,an appropriate amount of phenolphthalein is added to the solution as anindicator, and a 0.1N KOH aqueous solution is used for titration. Theacid value is then calculated by the following formula.

Acid value=0.1×Vf×56.1/(Wp×I)

In the formula, Vf represents the titer (mL) of the KOH aqueoussolution, Wp represents the weight (g) of the solution containing theweighed binder polymer, and I represents the measured proportion (mass%) of nonvolatile components in the solution containing the binderpolymer.When the binder polymer is added in admixture with volatile componentssuch as a synthetic solvent or diluting solvent, the acid value ismeasured after first heating for 1 to 4 hours at a temperature at least10° C. higher than the boiling point of the volatile components, beforeweighing, to remove the volatile components.

The photopolymerizable compound used as component (B) may be aphotopolymerizable compound with an ethylenic unsaturated group.

Examples of photopolymerizable compounds with ethylenic unsaturatedgroups include monofunctional vinyl monomers, bifunctional vinylmonomers and polyfunctional vinyl monomers having at least threepolymerizable ethylenic unsaturated groups.

Examples of monofunctional vinyl monomers include (meth)acrylic acid,alkyl (meth)acrylate and monomers that are copolymerizable therewith,which were mentioned as monomers to be used for synthesis of thesuitable examples of copolymers for component (A).

Examples of bifunctional vinyl monomers include polyethylene glycoldi(meth)acrylate, trimethylolpropane di(meth)acrylate, polypropyleneglycol di(meth)acrylate, bisphenol A polyoxyethylenepolyoxypropylenedi(meth)acrylate(2,2-bis(4-(meth)acryloxypolyethoxypolypropoxyphenyl)propane), bisphenolA diglycidyl ether di(meth)acrylate and the like; and ester compounds ofpolybasic carboxylic acids (such as phthalic anhydride) and substanceshaving a hydroxyl group and an ethylenic unsaturated group(β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate and the like).

Examples of polyfunctional vinyl monomers having at least threepolymerizable ethylenic unsaturated groups include compounds obtained byreacting α,β-unsaturated saturated carboxylic acids with polyhydricalcohols, such as trimethylolpropane tri(meth)acrylate,tetramethylolmethane tri(meth)acrylate, tetramethylolmethanetetra(meth)acrylate, dipentaerythritol penta(meth)acrylate anddipentaerythritol hexa(meth)acrylate, and compounds obtained by addingα,β-unsaturated carboxylic acids to glycidyl group-containing compounds,such as trimethylolpropane-triglycidyl ether triacrylate.

Among these are preferred those containing a polyfunctional vinylmonomer having at least three polymerizable ethylenic unsaturatedgroups. From the viewpoint of ability to minimize electrode corrosionand facilitating development, there are preferred one or more selectedfrom among (meth)acrylate compounds having a pentaerythritol-derivedbackbone, (meth)acrylate compounds having a dipentaerythritol-derivedbackbone and (meth)acrylate compounds having atrimethylolpropane-derived backbone, and more preferred are one or moreselected from among (meth)acrylate compounds having adipentaerythritol-derived backbone and (meth)acrylate compounds having atrimethylolpropane-derived backbone.

A (meth)acrylate having a dipentaerythritol-derived backbone is an estercompound of dipentaerythritol and (meth)acrylic acid, and such estercompounds include compounds modified with alkyleneoxy groups. Theseester compounds preferably have 6 ester bonds per molecule, but they maybe mixtures of compounds with 1-5 ester bonds.

Also, a (meth)acrylate compound having a trimethylolpropane-derivedbackbone is an ester compound of trimethylolpropane and (meth)acrylicacid, and such ester compounds include compounds modified withalkyleneoxy groups. These ester compounds preferably have 3 ester bondsper molecule, but they may be mixtures of compounds with 1 to 2 esterbonds.

These compounds may be used alone or in combinations of two or moredifferent ones.

When a monomer having at least three polymerizable ethylenic unsaturatedgroups in the molecule is to be used in combination with amonofunctional vinyl monomer or a bifunctional vinyl monomer, there areno particular restrictions on the proportion in which they are used, butfrom the viewpoint of the photocuring property and minimizing electrodecorrosion, the proportion of the monomer having at least threepolymerizable ethylenic unsaturated groups in the molecule is preferably30 parts by mass or greater, more preferably 50 parts by mass or greaterand even more preferably 75 parts by mass or greater, with respect to100 parts by mass as the total of the photopolymerizable compound in thephotosensitive resin composition.

The content of component (A) and component (B) in the photosensitiveresin composition of this embodiment is preferably 35 to 85 parts bymass of component (A) and 15 to 65 parts by mass of component (B), morepreferably 40 to 80 parts by mass of component (A) and 20 to 60 parts bymass of component (B), even more preferably 50 to 70 parts by mass ofcomponent (A) and 30 to 50 parts by mass of component (B) and mostpreferably 55 to 65 parts by mass of component (A) and 35 to 45 parts bymass of component (B), with respect to 100 parts by mass as the total ofcomponent (A) and component (B). Particularly from the viewpoint ofmaintaining transparency and pattern formability, the contents ofcomponent (A) and component (B) are preferably component (A) at 35 partsby mass or greater, more preferably 40 parts by mass or greater, evenmore preferably 50 parts by mass or greater and most preferably 55 partsby mass or greater, with respect to 100 parts by mass as the total ofcomponent (A) and component (B).

If the contents of component (A) and component (B) are within thisrange, it will be possible to obtain adequate sensitivity whileguaranteeing sufficient coatability or film properties of thephotosensitive element, and to adequately ensure the photocuringproperty, developability and electrode corrosion.

The photosensitive resin composition of this embodiment contains as anessential component an oxime ester compound and/or a phosphine oxidecompound as a photopolymerization initiator which is component (C). Byincluding an oxime ester compound and/or a phosphine oxide compound, itis possible to form a resin cured film pattern having sufficientresolution even with a thin-film having a thickness of 10 μm or smalleron the base material. It is also possible to form a resin cured filmpattern with excellent transparency.

The reason for this obtained effect is conjectured by the presentinventors to be as follows. Firstly, the present inventors believe thatone factor for the reduced sensitivity is that a smaller photosensitivelayer thickness increases the effect of light scattering through thebase material, generating halation. The present inventors presume that,for this embodiment, the oxime site in the oxime ester compound or thephosphine oxide site in the phosphine oxide compound has relatively highphotodecomposition efficiency and a suitable threshold value such thatit does not decompose with scant levels of leaked light, and thereforethe effect of leaked light is minimized and consequently sufficientresolution is obtained.

The oxime ester compound may be a compound represented by the followingformula (C-1) or formula (C-2). From the viewpoint of fast-curingproperties and transparency, a compound represented by the followingformula (C-1) is preferred.

In formula (C-1), R¹ represents a C1-12 alkyl or C3-20 cycloalkyl group.So long as the effect of the invention is not impeded, a substituent maybe present on the aromatic ring in formula (C-1).

In formula (C-1), R¹ is preferably a C3-10 alkyl or C4-15 cycloalkylgroup, and more preferably a C4-8 alkyl or C4-10 cycloalkyl group.

In formula (C-2), R² represents hydrogen or a C1-12 alkyl group, R³represents a C1-12 alkyl or C3-20 cycloalkyl group, R⁴ represents aC1-12 alkyl group and R⁵ represents a C1-20 alkyl or aryl group. Thesymbol p1 represents an integer of 0-3. When p1 is 2 or greater, themultiple R⁴ groups may be the same or different. The carbazole ring mayalso have a substituent so long as the effect of the invention is notimpeded.

In formula (C-2), R² is preferably a C1-12 alkyl group, more preferablya C1-8 alkyl group and even more preferably a C1-4 alkyl group.

In formula (C-2), R³ is preferably a C1-8 alkyl or C4-15 cycloalkylgroup, more preferably a C1-4 alkyl or C4-10 cycloalkyl group, and mostpreferably an ethyl group.

The compound represented by formula (C-1) may be 1,2-octanedione,1-[4-(phenylthio)-,2-(O-benzoyloxime)] or the like. The compoundrepresented by formula (C-2) may be ethanone,1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime).The compound 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyloxime)] isavailable as IRGACURE OXE 01 (trade name of BASF Corp.). Also, ethanone,1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-,1-(O-acetyloxime) iscommercially available as IRGACURE OXE 02 (trade name of BASF Corp.).These may be used alone or in combinations of two or more.

The compound 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyloxime)] isespecially preferred for formula (C-1). Particularly preferred forformula (C-2) is ethanone,1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-,1-(O-acetyloxime).

The phosphine oxide compound may be a compound represented by thefollowing formula (C-3) or formula (C-4). From the viewpoint offast-curing properties and transparency, a compound represented by thefollowing formula (C-3) is preferred.

In formula (C-3), R⁶, R⁷ and R⁸ each independently represent a C1-20alkyl or aryl group. In formula (C-4), R⁹, R¹⁰ and R¹¹ eachindependently represent a C1-20 alkyl or aryl group.

When R⁶, R⁷ or R⁸ in formula (C-3) is a C1-20 alkyl group, or when R⁹,R¹⁰ or R¹¹ in formula (C-4) is a C1-20 alkyl group, the alkyl group maybe straight-chain, branched-chain or cyclic, and more preferably thenumber of carbon atoms of the alkyl group is 5-10.

When R⁶, R⁷ or R⁸ in formula (C-3) is an aryl group or when R⁹, R¹⁰ orR¹¹ in formula (C-4) is an aryl group, the aryl group may be optionallysubstituted. Examples of substituents include C1-6 alkyl and C1-4 alkoxygroups.

Of these, R⁶, R⁷ and R⁸ in formula (C-3) are preferably aryl groups.Also, R⁹, R¹⁰ and R¹¹ in formula (C-4) are preferably aryl groups.

The compound represented by formula (C-3) is preferably2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, in consideration oftransparency of the protective coat to be formed and pattern formabilitywith a film thickness of 10 μm or smaller. The compound2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is commerciallyavailable as LUCIRIN TPO (trade name of BASF Corp.), for example.

Component (C) may be used in combination with a photoinitiator otherthan the oxime ester compound and phosphine oxide compound. Examples ofphotopolymerization initiators other than oxime ester compounds andphosphine oxide compounds include aromatic ketones such as benzophenone,4-methoxy-4′-dimethylaminobenzophenone and2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propanone-1;benzoinether compounds such as benzoinmethyl ether, benzoinethyl etherand benzoinphenyl ether; benzoin compounds such as benzoin,methylbenzoin and ethylbenzoin; benzyl derivatives such asbenzyldimethylketal; acridine derivatives such as 9-phenylacridine and1,7-bis(9,9′-acridinyl)heptane; N-phenylglycine and N-phenylglycinederivatives; coumarin-based compounds; and oxazole-based compounds. Acombination of a thioxanthone-based compound and tertiary amine compoundmay also be used, such as a combination of diethylthioxanthone anddimethylaminobenzoic acid.

The content of the photopolymerization initiator as component (C) ispreferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts bymass and more preferably 2 to 5 parts by mass, with respect to 100 partsby mass as the total of component (A) and component (B).

The content of component (C) is preferably 0.1 part by mass or greaterfrom the viewpoint of excellent photosensitivity and resolution, and itis preferably no greater than 20 parts by mass from the viewpoint ofvisible light transmittance.

The photosensitive resin composition of this embodiment may furthercontain an ultraviolet absorber (hereunder also referred to as“component (D)”). From the viewpoint of reflected light absorption theultraviolet absorber is preferably one with excellent absorbing powerfor ultraviolet rays with wavelengths of up to 380 nm, and from theviewpoint of transparency it is preferably one with low absorption forvisible light with wavelengths of 400 nm and longer. Specifically, theseinclude ultraviolet absorbers with maximum absorption wavelengths of upto 360 nm.

Examples of ultraviolet absorbers include oxybenzophenone-basedcompounds, benzotriazole-based compounds, salicylic acid ester-basedcompounds, benzophenone-based compounds, diphenyl acrylate-basedcompounds and nickel complex salt-based compounds. Particularlypreferred ultraviolet absorbers are diphenyl acrylate-based compoundssuch as diphenyl cyanoacrylate.

The content of the ultraviolet absorber as component (D) is preferably0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass and morepreferably 2 to 10 parts by mass, with respect to 100 parts by mass asthe total of component (A) and component (B).

From the viewpoint of excellent resolution, the content of component (D)is preferably 0.1 part by mass or greater, and from the viewpoint ofavoiding increased absorption on the surface of the composition duringactive light irradiation that results in insufficient photocuring in theinterior, it is preferably no greater than 30 parts by mass.

The photosensitive resin composition of this embodiment may alsocontain, if necessary, a tackifier such as a silane coupling agent, or aleveling agent, plasticizer, filler, antifoaming agent, flame retardant,stabilizer, antioxidant, aromatic, thermal crosslinking agent,polymerization inhibitor or the like, at about 0.01 to 20 parts by masseach with respect to 100 parts by mass as the total of component (A) andcomponent (B). They may be used alone or in combinations of two or more.

The minimum visible light transmittance of the photosensitive resincomposition of this embodiment at 400 to 700 nm is preferably 85% orgreater, more preferably 92% or greater and even more preferably 95% orgreater.

The visible light transmittance of the photosensitive resin compositionis determined in the following manner First, a support film is coatedwith a coating solution containing the photosensitive resin composition,to a post-drying thickness of 10 μm or smaller, and it is dried to forma photosensitive resin composition layer (photosensitive layer). Next,it is laminated onto a glass panel using a laminator, with thephotosensitive resin composition layer (photosensitive layer) incontact. A measuring sample is thus obtained having a photosensitiveresin composition layer and a support film laminated on a glass panel.The obtained measuring sample is then irradiated with ultraviolet raysto photocure the photosensitive resin composition layer, after which anultraviolet and visible spectrophotometer is used to measure thetransmittance in a measuring wavelength range of 400 to 700 nm.

The “preferred transmittance” means the minimum transmittance in thespecified wavelength range.

If the transmittance is at least 85% in a wavelength range of 400 to 700nm, which are light rays in the ordinary visible light wavelength range,for example, when a transparent electrode in the sensing region of atouch panel (touch sensor) is to be protected, or when the protectivecoat is visible from the edges of the sensing region after a metal layer(for example, a copper layer formed on an ITO electrode) in the frameregion of a touch panel (touch sensor) has been protected, it will bepossible to satisfactorily minimize reduction in the image displayquality, color shade and brightness in the sensing region.

Also, the photosensitive resin composition of this embodiment has avalue of preferably −0.2 to 1.0, more preferably 0.0 to 0.7 and evenmore preferably 0.1 to 0.4 for b* based on the CIELAB color system, whenthe protective coat has been formed. As with a minimum visible lighttransmittance of 85% or greater, b* is preferably −0.2 to 0.8 from theviewpoint of preventing reduction in image display quality and colorshade in the sensing region. Measurement of b* based on the CIELAB colorsystem can be accomplished, for example, using a “CM-5”spectrocolorimeter by Konica Minolta Holdings, Inc., forming aphotosensitive resin composition layer with a thickness of 10 μm orsmaller on a glass panel with a b* value of 0.1 to 0.2 and a thicknessof 0.7 mm, irradiating it with ultraviolet rays to photocure thephotosensitive resin composition layer, and then performing measurementwith a D65 light source and the viewing angle set to 2°.

Also, from the viewpoint of further increasing the resolution, thephotosensitive resin composition of this embodiment preferably has anabsorbance of no greater than 0.4 at 365 nm. Also, the absorbance at 334nm is preferably 0.4 or greater. If the photosensitive layer has suchabsorption properties, leaked light will be absorbed more easily, and itwill be possible to minimize decomposition of the oxime ester compoundor phosphine oxide compound by leaked light.

The absorbance can be measured using a UV spectrophotometer (U-3310spectrophotometer by Hitachi, Ltd.). The measurement is carried out byplacing on the measuring side a photosensitive element having aphotosensitive layer made of the photosensitive resin composition formedto the desired film thickness on a support film, placing the supportfilm on the reference side, and conducting continuous measurement inabsorbance mode up to 300 to 700 nm, and reading off the values for 334nm and 365 nm.

The method of adjusting the absorbance in the aforementioned range maybe, for example, mixture of the oxime ester compound and/or phosphineoxide compound and the ultraviolet absorber, or control of the filmthickness of the photosensitive layer.

The photosensitive resin composition of this embodiment may be used toform a photosensitive layer on a base material. For example, a coatingsolution that can be obtained by uniformly dissolving or dispersing thephotosensitive resin composition in a solvent may be coated on a basematerial to form a coating film, and the solvent removed by drying toform a photosensitive layer.

The solvent used may be a ketone, aromatic hydrocarbon, alcohol, glycolether, glycol alkyl ether, glycol alkyl ether acetate, ester ordiethylene glycol, from the viewpoint of the solubility of eachcomponent and ease of coating film formation. These solvents may be usedalone, or a mixed solvent may be used, comprising two or more differentsolvents.

Preferred for use among these solvents are ethyleneglycol monobutylether acetate, diethyleneglycol monoethyl ether acetate,diethyleneglycol diethyl ether, diethyleneglycol ethyl methyl ether,diethyleneglycol dimethyl ether, propyleneglycol monomethyl ether andpropyleneglycol monomethyl ether acetate.

The photosensitive resin composition of the invention is preferably usedto form a photosensitive film, as for a photosensitive element. Bylaminating a photosensitive film on a base material with an electrodefor a touch panel, it is possible to significantly contribute toshortening of the production process and reduction of costs, by allowinga roll-to-roll process to be easily accomplished and by shortening thesolvent drying step, for example.

The photosensitive layer 20 of the photosensitive element 1 can beformed by preparing a coating solution containing the photosensitiveresin composition of this embodiment, and coating and drying it on asupport film 10. The coating solution can be obtained by uniformlydissolving or dispersing each of the components used to form thephotosensitive resin composition of this embodiment, in a solvent.

There are no particular restrictions on the solvent, and a known one maybe used such as acetone, methyl ethyl ketone, methyl isobutyl ketone,toluene, methanol, ethanol, propanol, butanol, methylene glycol,ethylene glycol, propylene glycol, ethyleneglycol monomethyl ether,ethyleneglycol monoethyl ether, diethyleneglycol dimethyl ether,diethyleneglycol ethyl methyl ether, diethyleneglycol diethyl ether,propyleneglycol monomethyl ether, ethyleneglycol monobutyl etheracetate, diethyleneglycol monoethyl ether acetate, propyleneglycolmonomethyl ether acetate, chloroform or methylene chloride, for example.These solvents may be used alone, or a mixed solvent may be used,comprising two or more different solvents.

The coating method may be, for example, doctor blade coating, Meyer barcoating, roll coating, screen coating, spinner coating, ink jet coating,spray coating, dip coating, gravure coating, curtain coating or diecoating.

There are no particular restrictions on the drying conditions, but thedrying temperature is preferably 60° C. to 130° C. and the drying timeis preferably 0.5 to 30 minutes.

The thickness of the photosensitive layer is preferably 1 μm to 9 μm,more preferably 1 μm to 8 μm, even more preferably 2 μm to 8 μm and mostpreferably 3 μm to 8 μm, as the post-drying thickness, in order toexhibit an adequate effect for electrode protection and to reduce to aminimum any level differences on the touch panel (touch sensor) surfacethat are produced by partial electrode-protecting coat formation.

The minimum visible light transmittance of the photosensitive layer 20for this embodiment is preferably 85% or greater, more preferably 92% orgreater and even more preferably 95% or greater. Also, thephotosensitive layer 20 has a value of preferably −0.2 to 1.0, morepreferably 0.0 to 0.7 and even more preferably 0.1 to 0.4 for b* basedon the CIELAB color system, when the protective coat has been formed.

In addition, the absorbance of the photosensitive layer 20 at 365 nm ispreferably no greater than 0.4. Also, the absorbance at 334 nm ispreferably 0.4 or greater.

The viscosity of the photosensitive layer 20 at 30° C. is preferably 15to 100 mPa·s, more preferably 20 to 90 mPa·s and even more preferably 25to 80 mPa·s, from the viewpoint of preventing, for a period of one monthor longer, exudation of the photosensitive resin composition from theedges of the photosensitive element 1 when the photosensitive elementhas been taken up into a roll, and from the viewpoint of preventingexposure defects and development residue during irradiation of activelight rays, caused by adhesion of fragments of the photosensitive resincomposition on the substrate when the photosensitive element 1 is cut.

The viscosity is the value obtained by forming a circular film with adiameter of 7 mm and a thickness of 2 mm from the photosensitive resincomposition as a measuring sample, measuring the rate of change inthickness upon adding a load of 1.96×10⁻² N at 30° C. and 80° C. in thethickness direction of the sample, and calculating the viscosity fromthe change in thickness, assuming a Newtonian fluid.

The protective film 30 (cover film) may be, for example, a film composedof polyethylene, polypropylene, polyethylene terephthalate,polycarbonate, polyethylene-vinyl acetate copolymer orpolyethylene-vinyl acetate copolymer, or a laminated film ofpolyethylene-vinyl acetate copolymer and polyethylene.

The thickness of the protective film 30 is preferably about 5 to 100 μm,but from the viewpoint of curled storage as a roll, it is preferably nogreater than 70 μm, more preferably no greater than 60 μm, even morepreferably no greater than 50 μm and most preferably no greater than 40μm.

The photosensitive element 1 may be placed in curled storage as a roll,or used directly.

According to the invention, a coating solution containing thephotosensitive resin composition of this embodiment and a solvent iscoated onto a base material having an electrode for a touch panel, anddried to form a photosensitive layer 20 composed of the photosensitiveresin composition. For this purpose as well, the photosensitive layerpreferably satisfies the aforementioned conditions for film thickness,visible light transmittance, CIELAB color system b* value andabsorbance.

A method of forming a protective coat on an electrode for a touch panelwill now be described, as an embodiment of a method for forming a resincured film pattern according to the invention. FIG. 2 is a schematiccross-sectional view for illustration of an example of a method forforming a resin cured film pattern according to the invention.

The method for forming a protective coat on an electrode for a touchpanel according to this embodiment comprises a first step in which aphotosensitive layer 20 with a thickness of 10 μm or smaller, comprisinga photosensitive resin composition according to this embodiment isformed on a base material 100 having electrodes for a touch panel 110and 120, a second step in which prescribed sections of thephotosensitive layer 20 are cured by irradiation with active light raysincluding ultraviolet rays, and a third step in which the photosensitivelayer at the sections other than the prescribed sections (the sectionsof the photosensitive layer that have not been irradiated with activelight rays) are removed after the irradiation with active light rays, toform a protective coat 22 comprising a cured film pattern of thephotosensitive resin composition covering all or a portion of theelectrodes. A protective coat-covered touch panel (touch sensor) 200 isthus obtained as a touch input sheet.

The base material 100 to be used for this embodiment may be a substratesuch as a glass plate, plastic sheet or ceramic sheet commonly used fortouch panels (touch sensors). On the substrate there is provided anelectrode for a touch panel on which the resin cured film is to beformed as a protective coat. The electrode may be an ITO, Cu, Al or Moelectrode, or TFT. An insulating layer may also be provided on thesubstrate between the substrate and the electrode.

The base material 100 having electrodes for a touch panel 110 and 120shown in FIG. 2 can be obtained by the following procedure, for example.After forming a metal film by sputtering in the order ITO, Cu on a basematerial 100 such as a PET film, a photosensitive film for etching isattached onto the metal film, a desired resist pattern is formed, andthe unwanted Cu is removed with an etching solution such as an ironchloride aqueous solution, after which the resist pattern is peeled off

In the first step of this embodiment, the protective film 30 of thephotosensitive element 1 of this embodiment is removed and then thephotosensitive layer 20 is transferred onto the surface of the basematerial 100 on which the electrodes for a touch panel 110 and 120 areformed, by contact bonding while heating the photosensitive element, toaccomplish lamination (see FIG. 2(A)).

The contact bonding means may be a contact bonding roll. The contactbonding roll may be one provided with heating means to allowthermocompression bonding.

The heating temperature for thermocompression bonding is preferably 10°C. to 180° C., more preferably 20° C. to 160° C. and even morepreferably 30° C. to 150° C. so that the constituent components of thephotosensitive layer 20 will be more resistant to thermosetting orthermal decomposition, while ensuring sufficient adhesiveness betweenthe photosensitive layer 20 and the base material 100 and sufficientadhesiveness between the photosensitive layer 20 and the electrodes fora touch panel 110 and 120.

Also, the contact bonding pressure during thermocompression bonding ispreferably 50 to 1×10⁵ N/m, more preferably 2.5×10² to 5×10⁴ N/m andeven more preferably 5×10² to 4×10⁴ N/m as linear pressure, from theviewpoint of minimizing deformation of the base material 100 whileensuring sufficient adhesiveness between the photosensitive layer 20 andthe base material 100.

If the photosensitive element 1 is heated in this manner it will not benecessary to perform preheating treatment of the base material, althoughpreheating treatment of the base material 100 is preferred from theviewpoint of further increasing adhesiveness between the photosensitivelayer 20 and the base material 100. The preheating temperature ispreferably 30° C. to 180° C.

For this embodiment, instead of using a photosensitive element, acoating solution containing the photosensitive resin composition of thisembodiment and a solvent may be prepared and coated and dried onto thesurface of the base material 100 on which the electrodes for a touchpanel 110 and 120 have been formed, to form a photosensitive layer 20.

The photosensitive layer 20 preferably satisfies the aforementionedconditions for film thickness, visible light transmittance, CIELAB colorsystem b* value and absorbance.

In the second step of this embodiment, active light rays L areirradiated in a pattern on prescribed sections of the photosensitivelayer 20, through a photomask 130 (see FIG. 2(B)).

For irradiation of the active light rays, if the support film 10 on thephotosensitive layer 20 is transparent it will be possible to irradiatethe active light rays directly, but if it is opaque the active lightrays are irradiated after removing it. From the viewpoint of protectingthe photosensitive layer 20, preferably a transparent polymer film isused as the support film 10 and the polymer film is left on it, with theactive light irradiation being performed through it.

The active light ray light source used for irradiation of the activelight rays L may be a known active light source such as a carbon arclamp, ultra-high-pressure mercury lamp, high-pressure mercury lamp orxenon lamp, with no particular restrictions so long as the ultravioletrays can be effectively emitted.

The exposure dose for the active light rays L will usually be 1×10² to1×10⁴ J/m², and the irradiation may also be accompanied by heating. Ifthe active light ray exposure dose is less than 1×10² J/m² thephotocuring effect will tend to be inadequate, and if it is greater than1×10⁴ J/m² the photosensitive layer 20 will tend to undergodiscoloration.

For this embodiment, preferably the photosensitive layer 20 hasabsorbance at 365 nm of no greater than 0.4 and absorbance at 334 nm of0.4 or greater, and the active light ray light source is a combinationof an ultra-high-pressure mercury lamp and a UV laser having oscillationat 355 nm or 364 nm.

In the third step of this embodiment, the photosensitive layer that hasbeen irradiated with active light rays is developed with a developingsolution to remove the sections that have not been exposed to activelight rays (i.e. the sections other than the prescribed sections of thephotosensitive layer), to form a protective coat 22 composed of a curedfilm pattern of the photosensitive resin composition of this embodimentwith a thickness of 10 μm or smaller, covering all or a portion of theelectrode (see FIG. 2(C)). The protective coat 22 formed may have aprescribed pattern.

When the support film 10 is layered on the photosensitive layer 20 afterirradiation with active light rays, it is first removed, and thendevelopment is carried out with a developing solution for removal of thesections that have not been exposed to the active light rays.

The developing method preferably accomplishes development by a knownmethod such as spraying, showering, reciprocal dipping, brushing orscrapping using a known developing solution such as an aqueous alkalisolution, aqueous developing solution or organic solvent, and removal ofthe unwanted sections, and it is preferred to use an aqueous alkalisolution from the viewpoint of the environment and safety.

The base of the aqueous alkali solution may be an alkali hydroxide (suchas a hydroxide of lithium, sodium or potassium), an alkali carbonate(such as a carbonate or bicarbonate of lithium, sodium or potassium), analkali metal phosphate (such as potassium phosphate or sodiumphosphate), an alkali metal pyrophosphate (such as sodium pyrophosphateor potassium pyrophosphate), tetramethylammonium hydroxide,triethanolamine or the like, with tetramethylammonium hydroxide beingpreferred among these.

A sodium carbonate aqueous solution is also preferred for use, and forexample, a dilute sodium carbonate solution (0.5 to 5 mass % aqueoussolution) at 20° C. to 50° C. is preferably used.

The developing temperature and time can be adjusted to match thedevelopability of the photosensitive resin composition for thisembodiment.

The aqueous alkali solution may also contain added surfactants,antifoaming agents, and small amounts of organic solvents to acceleratedevelopment.

After development, the base of the aqueous alkali solution remaining onthe photosensitive layer 20 after photocuring may be subjected to acidtreatment (neutralizing treatment) by a known method such as spraying,reciprocal dipping, brushing, scrapping or the like using an organicacid or inorganic acid, or an aqueous solution of such acids.

A step of rinsing may also be carried out after acid treatment(neutralizing treatment).

Following development, the cured film pattern may be further cured byirradiation with active light rays (for example, 5×10³ to 2×10⁴ J/m²),if necessary. The photosensitive resin composition of this embodimentexhibits excellent adhesiveness for metals even without a heating stepafter development, but if necessary it may be subjected to heattreatment (80° C. to 250° C.) instead of irradiation with active lightrays or in combination with irradiation with active light rays, afterdevelopment.

Thus, the photosensitive resin composition and photosensitive element ofthis embodiment is suitable for use for formation of a resin cured filmpattern. Also, the photosensitive resin composition and photosensitiveelement of this embodiment are suitable for formation of a resin curedfilm pattern as a protective coat on an electrode for a touch panel (useas a resin cured film pattern forming material). For this use of thephotosensitive resin composition, a coating solution in admixture with asolvent may be used to form the protective coat.

The invention can also provide a material for forming a resin cured filmpattern, comprising a photosensitive resin composition according to theinvention. The resin cured film pattern-forming material may comprise aphotosensitive resin composition of the embodiment described above, andit is preferably a coating solution further containing the solventmentioned above.

An example of a part using a protective coat of the invention will nowbe described with reference to FIG. 3, FIG. 4 and FIG. 5. FIG. 3 is aschematic top view showing an example of an electrical capacitance-typetouch panel. The touch panel illustrated in FIG. 3 has a touch screen102 for detection of touch location coordinates on one side of atransparent substrate 101, and provided on the substrate 101 aretransparent electrodes 103 and transparent electrodes 104 for detectionof changes in electrostatic capacity in this region. The transparentelectrodes 103 and transparent electrodes 104 detect the X-coordinateand Y-coordinate, respectively, of the touch location.

On the transparent base 101 there are provided lead wirings 105 totransmit touch location detection signals from the transparentelectrodes 103 and transparent electrodes 104 to an external circuit.Also, the lead wirings 105 and the transparent electrodes 103 andtransparent electrodes 104 are connected by connecting electrodes 106provided on the transparent electrodes 103 and transparent electrodes104. On the side opposite the connecting sections between the leadwirings 105 and the transparent electrodes 103 and transparentelectrodes 104, there are provided connecting terminals 107 with anexternal circuit. The photosensitive resin composition of the inventioncan be suitably used to form a resin cured film pattern as a protectivecoat 122 for the lead wirings 105, connecting electrodes 106 andconnecting terminals 107. This allows simultaneous protrusion of theelectrodes in the sensing region. In FIG. 3, the protective coat 122protects the lead wirings 105, connecting electrodes 106, some of theelectrodes in the sensing region and some of the connecting terminals107, but the location where the protective coat is provided may bechanged as appropriate. For example, as shown in FIG. 4, the protectivecoat 123 may be provided protecting the entire touch screen 102.

The cross-sectional structure of the connecting section between thetransparent electrodes and lead wirings in the touch panel shown in FIG.3 will now be explained with reference to FIG. 5. FIG. 5 is a partialcross-sectional view of section C in FIG. 3 along line V-V, showing aconnecting section between a transparent electrode 104 and a lead wiring105. As shown in FIG. 5(A), the transparent electrode 104 and the leadwiring 105 are electrically connected via a connecting electrode 106.Also as shown in FIG. 5(A), part of the transparent electrode 104, andall of the lead wiring 105 and connecting electrode 106, are covered bythe resin cured film pattern as the protective coat 122. Likewise, thetransparent electrode 103 and the lead wiring 105 are electricallyconnected via a connecting electrode 106. As shown in FIG. 5(B), thetransparent electrode 104 and the lead wiring 105 are electricallyconnected in a direct manner. The photosensitive resin composition andphotosensitive element of the invention can be suitably used forformation of a resin cured film pattern as a protective coat in thestructural section described above.

A method for manufacturing a touch panel according to this embodimentwill now be explained. First, transparent electrodes (X-positioncoordinate) 103 are formed on a transparent electrode 101 provided on abase material 100. Next, transparent electrodes (Y-position coordinate)104 are formed. Formation of the transparent electrodes 103 andtransparent electrodes 104 may be accomplished by a method of etching atransparent electrode layer formed on the transparent base material 100.

Next, on the surface of the transparent base 101 there are formed leadwirings 105 for connection to an external circuit and connectingelectrodes 106 connecting the lead wirings with the transparentelectrodes 103 and transparent electrodes 104. The lead wirings 105 andconnecting electrodes 106 may be formed after formation of thetransparent electrodes 103 and transparent electrodes 104, or they maybe formed simultaneously during formation of the respective transparentelectrodes. Formation of the lead wirings 105 and connecting electrodes106 may involve metal sputtering followed by etching or the like. Thelead wirings 105 can be formed simultaneously with formation of theconnecting electrodes 106, for example, using a conductive pastematerial containing silver flakes, by screen printing or the like. Next,connecting terminals 107 are formed for connection between the leadwirings 105 and an external circuit.

In order to cover the transparent electrodes 103 and transparentelectrodes 104, the lead wirings 105, the connecting electrodes 106 andthe connecting terminals 107 formed by this step, the photosensitiveelement 1 of this embodiment is contact bonded and a photosensitivelayer 20 is provided over the electrodes. Next, the transferredphotosensitive layer 20 is exposed to active light rays L in a patternthrough a photomask having a prescribed shape. After irradiation of theactive light rays L, development is performed and all but the prescribedsections of the photosensitive layer 20 are removed, to form aprotective coat 122 composed of the cured sections of the photosensitivelayer 20. It is possible in this manner to produce a touch panelprovided with a protective coat 122.

EXAMPLES

The present invention will now be explained in greater detail byexamples. However, the present invention is not limited to the examplesdescribed below.

[Preparation of binder polymer solution (A1)]

In a flask equipped with a stirrer, a reflux condenser, an inert gasinlet and a thermometer there was charged component (1) listed in Table1, the temperature was raised to 80° C. under a nitrogen gas atmosphere,and component (2) listed in Table 1 was added dropwise uniformly over aperiod of 4 hours while maintaining a reaction temperature of 80° C.±2°C. After the dropwise addition of component (2), stirring was continuedat 80° C.±2° C. for 6 hours, to obtain a solution of a binder polymerwith a weight-average molecular weight of approximately 80,000 (45 mass% solid) (A1).

TABLE 1 Content (parts by mass) (A1) (1) Propyleneglycol 62 monomethylether Toluene 62 (2) Methacrylic acid 12 Methyl methacrylate 58 Ethylacrylate 30 2,2′-Azobis (isobutyronitrile) 1.2

The weight-average molecular weight (Mw) was measured by gel permeationchromatography (GPC), and calculation was performed using a standardpolystyrene calibration curve. The GPC conditions were as follows.

GPC conditionsPump: Hitachi L-6000 (product name of Hitachi, Ltd.).

Column: Gelpack GL-R420, Gelpack GL-R430, Gelpack GL-R440 (all

product names of Hitachi Chemical Co., Ltd.).

Eluent: Tetrahydrofuran

Measuring temperature: 40° C.Flow rate: 2.05 mL/minDetector: Hitachi L-3300 RI (product name of Hitachi, Ltd.).

[Acid Value Measuring Method]

The acid value was measured in the following manner First, a binderpolymer solution was heated at 130° C. for 1 hour to remove the volatilecomponents and obtain a solid portion. After then precisely weighing out1 g of polymer whose acid value was to be measured, 30 g of acetone wasadded to the polymer to form a homogeneous solution. Next, anappropriate amount of phenolphthalein was added to the solution as anindicator, and a 0.1N KOH aqueous solution was used for titration. Theacid value was then calculated by the following formula.

Acid value=0.1×Vf×56.1/(Wp×I)

In the formula, Vf represents the titer (mL) of the KOH aqueoussolution, Wp represents the weight (g) of the measured resin solution,and I represents the ratio (mass %) of nonvolatile components in themeasured resin solution.

Example 1 [Preparation of Coating Solution (V-1) ContainingPhotosensitive Resin Composition]

The materials listed in Table 2 were mixed for 15 minutes using astirrer, to prepare a coating solution (V-1) containing a photosensitiveresin composition for formation of a protective coat.

TABLE 2 Example 1 2 3 4 5 Component (A1)  60*¹  60*¹  60*¹  60*¹  60*¹(A) Component PET-30 40 40 40 40 40 (B) Component IRGACURE OXE 01  5 — 1  1  3 (C) IRGACURE OXE 02 —  1 — — — LUCIRIN TPO — — — —  5 OtherIRGACURE 184 — — — — — photopoly- IRGACURE 651 — — — — — merizableIRGACURE 369 — — — — — compound IRGACURE 907 — — — — — N-1717 — — — — —EAB — — — — — Component SB501 — —  5 — — (D) SB502 — — —  5 — OtherAntage W-500   0.1   0.1   0.1   0.1   0.1 SH30   0.1   0.1   0.1   0.1  0.1 Methyl ethyl ketone 50 50 50 50 50 *¹Indicates parts by mass ofbinder polymer after removal of solvent.

[Fabrication of Photosensitive Element (E-1)]

Using a polyethylene terephthalate film with a thickness of 50 μm as thesupport film, the coating solution (V-1) containing the photosensitiveresin composition prepared above was uniformly coated onto the supportfilm with a comma coater, and dried for 3 minutes at 100° C. with a hotair convection drier to remove the solvent, thereby forming aphotosensitive layer comprising the photosensitive resin composition(photosensitive resin composition layer). The thickness of the obtainedphotosensitive layer was 2.5 μm.

Next, a 25 μm-thick polyethylene film was attached as a cover film onthe obtained photosensitive layer, to fabricate a photosensitive element(E-1) for formation of a protective coat.

[Measurement of Cured Film Transmittance]

While releasing the polyethylene film as the cover film of the obtainedphotosensitive element (E-1), a laminator (trade name HLM-3000 byHitachi Chemical Co., Ltd.) was used for lamination on a 1 mm-thickglass panel with the photosensitive layer in contact therewith, underconditions with a roll temperature of 120° C., a substrate feed rate of1 m/min and a contact bonding pressure (cylinder pressure) of 4×10⁵ Pa(because a substrate with a thickness of 1 mm and 10 cm length×10 cmwidth was used, the linear pressure at this time was 9.8×10³ N/m), toform a stack with the photosensitive layer and support film laminated onthe glass panel.

Next, a parallel ray exposure device (EXM1201 by Orc Manufacturing Co.,Ltd.) was used to expose the photosensitive layer of the obtained stackto ultraviolet rays with an exposure dose of 5×10² J/m² (measured valuefor i-rays (wavelength of 365 nm)) from the photosensitive layer side,and then the support film was removed to obtain a transmittancemeasuring sample having a cured film pattern of a photosensitive layerwith a thickness of 2.5 μm.

Next, the visible light transmittance of the obtained sample at ameasuring wavelength range of 400 to 700 nm was measured using anultraviolet and visible spectrophotometer (U-3310) by HitachiHigh-Technologies Corp. The transmittance of the obtained cured film was97% at a wavelength of 700 nm, 96% at a wavelength of 550 nm and 94% ata wavelength of 400 nm, and the minimum transmittance at 400 to 700 nmwas 94%, and therefore satisfactory transmittance was ensured.

[Measurement of b* Value of Cured Film]

While releasing the polyethylene film of the obtained photosensitiveelement (E-1), a laminator (trade name HLM-3000 by Hitachi Chemical Co.,Ltd.) was used for lamination on a 0.7 mm-thick glass panel with thephotosensitive layer in contact therewith, under conditions with a rolltemperature of 120° C., a substrate feed rate of 1 m/min and a contactbonding pressure (cylinder pressure) of 4×10⁵ Pa (because a substratewith a thickness of 1 mm and 10 cm length×10 cm width was used, thelinear pressure at this time was 9.8×10³ N/m), to form a substrate withthe photosensitive layer and support film laminated on the glass panel.

Next, a parallel ray exposure device (EXM1201 by Orc Manufacturing Co.,Ltd.) was used to expose the obtained photosensitive layer toultraviolet rays with an exposure dose of 5×10² J/m² (measured value fori-rays (wavelength of 365 nm)) from the photosensitive layer side, andthen the support film was removed and ultraviolet rays were furtherirradiated at an exposure dose of 1×10⁴ J/m² (measured value for i-rays(wavelength of 365 nm)) from the photosensitive layer side, to obtain ab* value measuring sample having a cured film pattern of thephotosensitive layer with a thickness of 2.5 μm.

The obtained sample was then used for measurement of the b* value basedon the CIELAB color system, using a spectrocolorimeter (CM-5) by KonicaMinolta Holdings, Inc., with the light source set to D65 and the viewingangle to 2°.

The b* value of the cured film was 0.45, thus confirming that it had asatisfactory b* value.

[Measurement of Photosensitive Layer Absorbance]

A UV spectrophotometer (U-3310 spectrophotometer by HitachiHigh-Technologies Corp.) was used for the measurement. The measurementwas carried out by placing the photosensitive element on the measuringside, placing the support film on the reference side, and conductingcontinuous measurement in absorbance mode up to 300 to 700 nm, andreading off the values for 334 nm and 365 nm.

The obtained absorbance values were 0.44 at 334 nm and 0.14 at 365 nm.

[Photosensitive Property of Photosensitive Layer]

While releasing the polyethylene film of the obtained photosensitiveelement, it was laminated on a PET film [thickness: 125 μm, trade nameA4300 by Toyobo, Ltd.] using a laminator (trade name: Model HLM-3000 byHitachi Chemical Co., Ltd.), under conditions with a roll temperature of120° C., a substrate feed rate of 1 m/min and a contact bonding pressure(cylinder pressure) of 4×10⁵ Pa. The active light irradiation wasperformed by placement on the Mylar PET of an exposure device with anEXM-1201 high-pressure mercury lamp (product of Orc Manufacturing Co.,Ltd.) and irradiating it with a prescribed dose of active light raysthrough the filter. Following active light ray irradiation it wasallowed to stand at room temperature for 10 minutes, and then thepolyethylene terephthalate was removed and the photosensitive resincomposition at the sections that had not been exposed to active lightrays were subjected to spray development for 60 seconds with 1% aqueoussodium carbonate at 30° C. Following spray development, an ultravioletirradiation device by Orc Manufacturing Co., Ltd. was used forultraviolet irradiation at 1 J/cm². The evaluation sensitivity was thenecessary exposure dose to obtain 6/21 steps with a 41-step tablet byHitachi Chemical Co., Ltd. Also, a PET photomask having a wiring patternwith a line width/space width ratio of 6/6 to 47/47 (unit: μm) wasfirmly attached, the pattern of the exposure dose obtained with 6/21steps was observed with an optical microscope and the resolution (μm)was determined from the line width (μm) remaining as a line-and-spacepattern.

Examples 2 to 5, Comparative Examples 1 to 6

Photosensitive elements were fabricated in the same manner as Example 1except for using coating solutions comprising the photosensitive resincompositions listed in Table 2 and Table 3, and the transmittancemeasurement, b* values, absorbances and photosensitive properties wereevaluated. The numerical values in Table 2 and Table 3 represent partsby mass.

TABLE 3 Comp. Ex. 1 2 3 4 5 6 Component (A1)  60*¹  60*¹  60*¹  60*¹ 60*¹  60*¹ (A) Component PET-30 40 40 40 40 40 40 (B) ComponentIRGACURE OXE 01 — — — — — — (C) IRGACURE OXE 02 — — — — — — LUCIRIN TPO— — — — — — Other IRGACURE 184  5 — — — — — photopoly- IRGACURE 651 —  5— — — — merizable IRGACURE 369 — — — —  3 — compound IRGACURE 907 — — —— —  3 N-1717 — —   0.2   0.2 — — EAB — —  1  2 — — Component SB501 — —— — — — (D) SB502 — — — — — — Other Antage W-500   0.1   0.1   0.1   0.1  0.1   0.1 SH30   0.1   0.1   0.1   0.1   0.1   0.1 Methyl ethyl ketone50 50 50 50 50 50 *¹Indicates parts by mass of binder polymer afterremoval of solvent.

The symbols for the components in Table 2 and Table 3 have the followingmeanings.

Component (A)

(A1): Propyleneglycol monomethyl ether/toluene solution of copolymerwith monomer mixing ratio of (methacrylic acid/methyl methacrylate/ethylacrylate=12/58/30 (mass ratio)), weight-average molecular weight:65,000, acid value: 78 mgKOH/g

Component (B)

PET-30: Pentaerythritol triacrylate (product of Nippon Kayaku Co., Ltd.)

Component (C)

IRGACURE OXE 01: 1,2-Octanedione,1-[(4-phenylthio)-,2-(O-benzoyloxime)](product of BASF)IRGACURE OXE 02:Ethanone,1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-,1-(O-acetyloxime)(product of BASF)LUCIRIN TPO: 2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide (product ofBASF)

Other Photopolymerization Initiators

IRGACURE 184: 1-Hydroxy-cyclohexyl-phenyl-ketone (product of BASF)IRGACURE 651: 2,2-Dimethoxy-1,2-diphenylethan-1-one (product of BASF)IRGACURE 369: 2-Benzyl-2-dimethylamino-1-(morpholinophenyl)-butanone-1(product of BASF)IRGACURE 907: 2-Methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one(product of BASF)N-1717: 1,7-bis(9-Acridinyl)heptane (product of Adeka Corp.)EAB: 4,4′-bis(Diethylamino)benzophenone (product of Hodogaya ChemicalCo., Ltd.)

Component (D)

SB501: Ethyl-2-cyano-3,3-diphenyl acrylate (product of Shipro Kasei Co.,Ltd.)SB502: 2′-Ethylhexyl-2-cyano-3,3-diphenyl acrylate (product of ShiproKasei Co., Ltd.)

Other Components

Antage W-500: 2,2′-Methylene-bis(4-ethyl-6-tert-butylphenol) (product ofKawaguchi Chemical Industry Co., Ltd.)SH30: Octamethylcyclotetrasiloxane (product of Dow Corning Toray)Methyl ethyl ketone: product of Tonen Chemical Co., Ltd.

As shown in Table 4 and Table 6, it was possible to achieve bothresolution and transparency with a film thickness of 2.5 μm, in Examples1, 2 and 5 which used an oxime ester compound or phosphine oxidecompound as the photopolymerization initiator. Furthermore, it waspossible to obtain even higher resolution in Examples 3 and 4 which alsoemployed an ultraviolet absorber. However, the reduction in resolutionwas considerable in Comparative Examples 1 to 6. Also, ComparativeExamples 3 and 4 had satisfactory resolution but exhibited yellowcoloration of the film.

Examples 6 to 10 and Comparative Examples 5 to 12

The same evaluation was conducted with a photosensitive layer filmthickness of 5 μm for Examples 1 to 5 and Comparative Examples 1 to 6(Examples 6 to 10 and Comparative Examples 5 to 12). Here, however, thenecessary exposure dose for [Photosensitive property of photosensitivelayer] was the exposure dose to obtain 10/41 steps with a 41-step tabletby Hitachi Chemical Co., Ltd. The results are shown in Table 5 and Table7 below.

TABLE 4 Example 1 Example 2 Example 3 Example 4 Example 5 Film thickness(μm) 2.5 2.5 2.5 2.5 2.5 Transmittance 700 nm 99 99 99 99 99 (%) 550 nm99 99 99 99 99 400 nm 94 93 97 97 95 Minimum transmittance 94 93 95 9595 at 400-700 nm (%) Absorbance 334 nm 0.44 0.42 0.70 0.70 0.45 365 nm0.14 0.12 0.11 0.12 0.20 b* 0.45 0.60 0.28 0.28 0.22 Sensitivity(mJ/cm²) 5 5 40 40 80 Resolution (x/x, μm) 25 30 22 22 25 Resolution(x/400, μm) 15 15 15 15 15 Resolution (400/x, μm) 30 45 25 25 30 ColorColorless, Colorless, Colorless, Colorless, Colorless, transparenttransparent transparent transparent transparent

TABLE 5 Example 6 Example 7 Example 8 Example 9 Example 10 Filmthickness (μm) 5 5 5 5 5 Transmittance 700 nm 98 98 98 98 98 (%) 550 nm98 98 98 98 98 400 nm 88 86 94 94 90 Minimum transmittance 88 86 90 9090 at 400-700 nm (%) Absorbance 334 nm 0.90 0.86 1.42 1.40 0.88 365 nm0.29 0.25 0.22 0.24 0.38 b* 0.92 0.98 0.58 0.56 0.42 Sensitivity(mJ/cm²) 15 15 120 120 240 Resolution (x/x, μm) 30 35 27 27 30Resolution (x/400, μm) 20 20 20 20 20 Resolution (400/x, μm) 30 45 25 2530 Color Colorless, Colorless, Colorless, Colorless, Colorless,transparent transparent transparent transparent transparent

TABLE 6 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Comp. Ex. 4 Comp. Ex. 5Comp. Ex. 6 Film thickness (μm) 2.5 2.5 2.5 2.5 2.5 2.5 Transmittance700 nm 99 94 99 99 99 99 (%) 550 nm 99 93 98 99 99 99 400 nm 99 95 85 8090 95 Minimum transmittance 95 95 85 80 90 95 at 400-700 nm (%)Absorbance 334 nm 0.01 0.01 0.90 1.54 1.60 0.36 365 nm 0.03 0.03 0.612.62 0.45 0.06 b* 0.22 0.25 4.20 7.00 0.5 0.28 Sensitivity (mJ/cm²) 540170 70 90 15 30 Resolution (x/x, μm) 40 35 25 25 40 >47 Resolution(x/400, μm) 40 25 8 12 35 >47 Resolution (400/x, μm) >47 >47 3230 >47 >47 Color Colorless, Colorless, Yellow, Yellow, Colorless,Colorless, transparent transparent transparent transparent transparenttransparent

TABLE 7 Comp. Ex. 7 Comp. Ex. 8 Comp. Ex. 9 Comp. Ex. 10 Comp. Ex. 11Comp. Ex. 12 Film thickness (μm) 5 5 5 5 5 5 Transmittance 700 nm 98 8898 98 98 98 (%) 550 nm 98 86 98 98 96 98 400 nm 98 90 81 90 72 64Minimum transmittance 90 90 81 90 72 64 at 400-700 nm (%) Absorbance 334nm 0.02 0.02 3.10 0.71 1.90 3.00 365 nm 0.06 0.06 0.66 0.12 1.25 5.24 b*0.44 0.5 1.1 0.56 8.6 14 Sensitivity (mJ/cm²) >500 >500 45 90 210 270Resolution (x/x, μm) >47 >47 45 >47 30 30 Resolution (x/400, μm) >47 >4740 >47 15 18 Resolution (400/x, μm) >47 >47 >47 >47 32 30 ColorColorless, Colorless, Colorless, Colorless, Yellow, Yellow, transparenttransparent transparent transparent transparent transparent

EXPLANATION OF SYMBOLS

1: Photosensitive element, 10: support film, 20: photosensitive layer,22: protective coat, 30: protective film, 100: base material, 101:transparent base, 102: touch screen, 103: transparent electrode(X-position coordinate), 104: transparent electrode (Y-positioncoordinate), 105: lead wiring, 106: connecting electrode, 107:connecting terminal, 110,120: electrodes for touch panel, 122,123:protective coats, 130: photomask, 200: touch panel.

1. A method for forming a resin cured film pattern comprising a firststep in which on a base material configured for use in a touch panelthere is formed a transparent photosensitive layer composed of atransparent photosensitive resin composition comprising a binder polymerwith a carboxyl group having an acid value of 75 mgKOH/g or greater, aphotopolymerizable compound and a photopolymerization initiator, asecond step in which prescribed sections of the transparentphotosensitive layer are cured by irradiation with active light rays,and a third step in which the sections of the transparent photosensitivelayer other than the prescribed sections are removed to form atransparent cured film pattern of the prescribed sections of thetransparent photosensitive layer, wherein the transparent photosensitiveresin composition comprises an oxime ester compound and/or a phosphineoxide compound as the photopolymerization initiator, and wherein thecured prescribed sections have a minimum visible light transmittance of85% or greater at 400 to 700 nm.
 2. The method for forming a resin curedfilm pattern according to claim 1, wherein the photosensitive resincomposition further comprises an ultraviolet absorber.
 3. The method forforming a resin cured film pattern according to claim 2, wherein theultraviolet absorber has a maximum absorption wavelength in a wavelengthrange of 360 nm or shorter.
 4. The method for forming a resin cured filmpattern according to claim 1, wherein the photosensitive layer has anabsorbance at 365 nm of no greater than 0.4 and an absorbance at 334 nmof 0.4 or greater.
 5. The method for forming a resin cured film patternaccording to claim 1, wherein the cured prescribed sections have a b*value of −0.2 to 1.0 based on the CIELAB color system.
 6. The method forforming a resin cured film pattern according to claim 1, wherein thebase material is provided with electrodes for the touch panel and aresin cured film pattern is formed as a protective coat on theelectrodes.
 7. The method for forming a resin cured film patternaccording to claim 1, wherein a photosensitive element is preparedcomprising a support film and the photosensitive layer composed of thephotosensitive resin composition provided on the support film, and thephotosensitive layer of the photosensitive element is transferred ontothe base material to provide the photosensitive layer.
 8. A method formanufacturing a touch panel comprising a step of forming, on a basematerial with an electrode for a touch panel, a resin cured film patternas a protective coat covering all or a portion of the electrode by themethod according to claim
 1. 9. The method for forming a resin curedfilm pattern according to claim 1, wherein the thickness of thephotosensitive layer is 10 μm or less.
 10. A photosensitive resincomposition to be used for formation of a resin cured film pattern,comprising a binder polymer with a carboxyl group having an acid valueof 75 mgKOH/g or greater, a photopolymerizable compound and aphotopolymerization initiator, the photopolymerization initiatorincluding an oxime ester compound and/or a phosphine oxide compound,wherein the photosensitive resin composition is configured to form atransparent resin cured film pattern on a base material of a touch panelsuch that the transparent resin cured film pattern comprises a resincured film having a minimum visible light transmittance of 85% orgreater at 400 to 700 nm.
 11. The photosensitive resin compositionaccording to claim 10, further comprising an ultraviolet absorber. 12.The photosensitive resin composition according to claim 11, wherein theultraviolet absorber has a maximum absorption wavelength in a wavelengthrange of 360 nm or shorter.
 13. The photosensitive resin compositionaccording to claim 10, wherein the photosensitive resin composition hasan absorbance at 365 nm of no greater than 0.4 and an absorbance at 334nm of 0.4 or greater.
 14. The photosensitive resin composition accordingto claim 10, wherein the resin cured film has a b* value of −0.2 to 1.0based on the CIELAB color system.
 15. A photosensitive elementcomprising a support film and a photosensitive layer composed of thephotosensitive resin composition according to claim 10 provided on thesupport film.
 16. The photosensitive element according to claim 15,wherein the thickness of the photosensitive layer is 10 μm or less. 17.A resin cured film comprising a cured photosensitive resin compositionaccording to claim
 10. 18. A touch panel comprising a base material onwhich a transparent cured film pattern is formed from the photosensitiveresin composition according to claim 10.